A356铝合金双重除气工艺研究

采用水模拟试验研究了两种旋转喷吹转子对气泡的影响,并分别采用透气砖、旋转喷吹和双重除气工艺对铝合金熔体除气,开发出一种双重除气工艺。结果表明,转子形状对铝液除气效果有较大影响,双层转子能够充分破碎气泡,并使气泡更加分散,起到良好的除气效果。旋转喷吹对底部铝液除气效果较差,而透气砖除气效率较低,采用透气砖和旋转喷吹双重除气,能够充分处理底部铝液中的气体,显著提高除气效率。     

恒流率条件下非润湿喷孔上气泡的形成

通过透气砖向金属液中鼓入惰性气体是一种重要的精炼工艺,具有搅拌熔池、提高反应速率以及去气去夹杂等作用,其应用日趋广泛。根据冶金动力学理论,精炼效率与气体在金属液中的行为密切相关。为此,有必要研究这类工艺的基础——恒流率条件下非润湿喷孔上气泡的形成及诸因素对气泡尺寸的影响.实验工作     

BUBBLE FORMATION FROM NON-WETTED ORIFICES UNDER CONSTANT FLOW RATE

<正> 通过透气砖向金属液中鼓入惰性气体是一种重要的精炼工艺,具有搅拌熔池、提高反应速率以及去气去夹杂等作用,其应用日趋广泛。根据冶金动力学理论,精炼效率与气体在金属液中的行为密切相关。为此,有必要研究这类工艺的基础——恒流率条件下非润湿喷孔上气泡的形成及诸因素对气泡尺寸的影响.实验工作     

铝熔体旋转喷吹净化动态水模拟试验研究

通过动态水模拟试验考察了喷头转速、气体流量和喷头浸入液体深度三个因素与气泡尺寸的关系,利用二次回归正交试验方法设计试验过程。试验结果表明,可以观察到气泡床的偏移,在特定的容积内喷头转速对气泡尺寸的影响最大,其次是气体流量,而喷头浸入深度对气泡尺寸影响较小。在现有的模拟试验条件下,当喷头转速215 r/min、气体流量2.94 m3/h、喷头浸入深度551 mm时,可以获得最理想的气泡尺寸。用相应设备处理铝熔体时,对铝熔体的含氢量进行测定。结果表明,在适宜的结构空间内,大叶轮、低转速的合理工艺组合可以获得较理想的除气效果。     

AZ91镁合金旋转喷吹除气理论分析及实验研究

通过分析旋转喷吹除气过程中氢在惰性气泡表面和金属熔体/空气界面的质量传输,建立适用于镁合金旋转喷吹除气的理论模型.通过计算,分析工艺参数对除气效率的影响.结果表明:随着旋转喷吹转速由230 r/min增大到330 r/min时,熔体中气泡总表面积由1.49×10-2m2增大到3.44×10-2m2,这增大了熔体中氢向气泡的单位时间扩散量,从而使除气效率随着转速的增加而增大.利用减压凝固方法对旋转喷吹除气的效果进行实验验证,实验结果与理论模型计算结果吻合较好.该模型可以用来指导镁合金熔体除气工艺的优化.     

旋转喷吹水模拟镁合金熔体除气

在镁合金旋转喷吹除气模型基础上,利用水模拟确定气泡总表面积,研究转速、气体流量及喷头和坩埚直径比对除气效率的影响.结果表明,转速和气体流量对除气效率影响较大,通常条件下高气体流量和高转速除气效率较高;喷头和坩埚直径比例在1:3到1:5之间变化时除气效率变化不显著.     

连铸中间包透气水口座砖吹氩冶金技术开发与应用

开发了一种新型的具有吹氩功能的中间包透气水口座砖,介绍了透气水口座砖的结构及工作原理,采用水模试验研究了透气水口座砖吹气量大小对中间包及结晶器内氩气量的分布及气泡大小的影响,试验结果表明:随着透气水口座砖吹气量的逐渐增大,结晶器内气泡的数量和直径都逐渐增大,合适的模拟吹气量为2~3 L/min。透气水口座砖用于板坯连铸机浇注生产超低碳铝镇静钢DC04的结果表明:该产品具有显著的去除钢水中非金属夹杂物及防止上水口和浸入水口结瘤的冶金效果,浸入式水口寿命由2~3炉提高到5~7炉。     

预热惰性气体对铝熔体除气效果的影响

为了充分发挥惰性气体对铝熔体的除气效果而又避免环境污染,提出预热惰性气体除气的新思路,设计简易预热装置,提高惰性气体气泡的入液温度。除气试验结果表明,在相同的熔炼条件下,预热惰性气体除气法可产生细小弥散的入液"热气泡",气泡不易长大且延长了气泡溢出液面的时间,当静置时间为20 min时,熔体含氢量可低至0.15 mL/(100 g Al),除气效果优于常规低温气体除气法的,是一种有效的环保型物理除气新工艺。     

透气砖过流精炼试验与研究

透气砖过流精炼是在采用N_2—Cl_2混合精炼十几年,取得了良好效果并对精炼器不断革新的基础上研究成功的。它的优点是:边出炉边精炼,省去原工艺的精炼时间;透气砖产生的气泡很小,因而能提高精炼效果;由于不用铁制     

熔体超声处理对AZ91镁合金除气的影响

研究了超声处理对AZ91镁合金除气效果的影响。结果表明,采用超声波处理可以有效的去除镁合金熔体中的气体,从而提高铸锭的致密度。超声除气效果与施加功率和处理时间密切相关。在本实验条件下:超声功率105 W,处理时间60 s时除气效果最好,除气率可达73%。超声波不仅具有良好的除气效果,而且可以细化铸锭的铸态组织,均匀细小的组织则有利于气泡的上浮和熔体补缩;经过超声处理后,铸锭的硬度值可从未处理的30.7增大至74,提高了141%。     

铝合金液除气板的试验研究

研究了两种材料制作的除气板,分析了有机添加物含量和工艺参数对除气板透气性的影响,分析了特制石墨除气板的气泡分布状态,并通过水模拟试验对工艺参数进行了优化.结果表明,两种除气板产生的气泡细小、均匀,数量适中,经对铝液的实际除气处理,ZLIOIA合金液的密度大于2.62g/cm3,针孔度等级小于二级.     

A new high shear degassing technology and mechanism for 7032 alloy

Degassing is very important for aluminum alloys especially for 7xxx series alloys.In the present study,a high shear technology was used to degas 7032 aluminum alloy in order to study its degassing efficiency.The experimental results showed that the high shear technology can significantly degas 7032 aluminum alloy.By applying intensive melt shearing and an Ar injection of 60 seconds,the density index,D_i,was reduced from13.25%to 0.28%and the hydrogen concentration was significantly reduced from 0.31 to 0.10 mL/100 g Al.Compared with the conventional rotary degassing,high shear technology showed a much higher degassing efficiency,achieving a lower concentration of hydrogen in a shorter time.The water simulation experiment was used to study the mechanism of the high degassing efficiency.The small bubble size and the uniform distribution of Ar bubbles with the application of high shear technology are believed to be the main cause for the high degassing efficiency.     

脉冲进气旋转喷吹技术的水力模拟

在铝合金熔体净化旋转喷吹技术的基础上 ,采用水力模拟实验研究了脉冲进气方式对气泡大小的影响。实验结果表明 :脉冲进气方式有利于产生射流 ,使气泡变小 ,并增加了气泡与熔体接触的比表面积 ,从而改善了除氢的动力学条件 ,有利于提高除氢效果。     

透气塞对保温炉铝液精炼效果的影响

论述了保温炉内通过透气塞对铝液进行精炼净化,去除杂质的方法,重点论述了透气塞精炼的优点、透气塞在保温炉内的分布状况,并对实际除氢效果进行了分析。对于85t矩形保温炉,采用18个透气塞精炼时,除氢效率能够达到30%~40%。通过优化透气塞在保温炉内的分布,改善透气塞与周围耐火材料的兼容性,能够显著提高除氢精炼的效果。     

碳化硅颗粒增强铝基复合材料的重熔和铸造工艺特征

介绍了SiC颗粒增强铸造铝基复合材料的铸锭重熔、除气和铸造过程的特征。由于颗粒的存在 ,这些工艺过程和普通铝合金有一定的差异。在铸锭重熔时 ,需要控制熔炼温度和对熔体施加搅拌 ,以防止颗粒反应和下沉。普通铝合金采用的熔盐和气体除气工艺不适合于复合熔体的除气精炼 ,而真空除气具有很好的效果。复合熔体具有高的粘度 ,流动性较差 ,在大气自由重力浇注时容易卷入气体而导致铸件气孔缺陷。为了防止铸件缺陷的形成 ,复合材料在大气自由重力浇注下的浇注系统需要设计集气、集渣冒口和阻流口等特殊组元。真空差压浇注工艺大大简化了浇注系统 ,降低了材料消耗 ,同时消除了大气自由重力浇注时容易产生的铸造缺陷。通过该工艺可获得形状复杂、表面光洁、尺寸精确的铝基复合材料精密铸件     

铝合金精炼与变质复合工艺的试验研究

研究了不同精炼处理工艺对铝液精炼效果的影响,分析了精炼工艺对不同变质剂变质效果的影响。结果表明,氩气旋转喷吹技术与盐类精炼复合的精炼工艺,可提高铝液的精炼效果;氩气旋转喷吹精炼与钠盐变质处理同时进行的复合工艺,可降低钠盐变质处理时的吸气倾向;氩气旋转喷吹精炼能减少铝液中锶的烧损,提高Sr的变质效果。     

Weibull analysis of fluidity and hardness of ultrasonical y degassed secondary Al7Si0.3Mg aluminum alloy

The influence of ultrasonic degassing process on fluidity and hardness of secondary Al7 Si0.3 Mg alloy castings was studied by Weibull analysis. This work makes a contribution about fluidity and hardness distribution of secondary aluminum alloys with ultrasonic degassing phenomena using a two-parameter form of Weibull analysis. Results show that both hardness and fluidity of alloy are improved after the ultrasonic degassing process. Average efficiency of ultrasonic degassing on fluidity measurements is 31.71%, whereas on hardness values is 8.48%. The Brinell hardness of 45.7 and fluidity of 19.5 of Weibull modulus were achieved as the most reliable and reproducible after 45 s ultrasonic degassing process against 15 s and 30 s ultrasonic degassing processes. The value of 70.08 HB is obtained from ultrosonic degassing, which is equivalent to sand casting of primary Al7 Si0.3 Mg aluminum alloy, and the highest value of 56.4 cm for 45 s after ultrasonic degassing of fluidity was measured.     

脉冲进气精炼铝合金熔体的水力模拟研究

本文将带气体动力脉冲器的转头应用于铝合金熔体净化旋转喷吹技术当中，并通过水力模拟实验，研究了脉冲进气方式对气泡大小的影响。结果表明：带气体动力脉冲器的转头可以产生强烈的脉冲射流，在相同的气体流量和转头转速等条件下，脉冲射流比连续射流更容易得到小尺寸气泡，更有利于氢的排除。     

Weibull analysis of fluidity and hardness of ultrasonically degassed secondary Al7Si0.3Mg aluminum alloy

The influence of ultrasonic degassing process on fluidity and hardness of secondary Al7Si0.3Mg alloy castings was studied by Weibull analysis. This work makes a contribution about fluidity and hardness distribution of secondary aluminum alloys with ultrasonic degassing phenomena using a two-parameter form of Weibull analysis. Results show that both hardness and fluidity of alloy are improved after the ultrasonic degassing process. Average efficiency of ultrasonic degassing on fluidity measurements is 31.71%, whereas on hardness values is 8.48%. The Brinell hardness of 45.7 and fluidity of 19.5 of Weibull modulus were achieved as the most reliable and reproducible after 45 s ultrasonic degassing process against 15 s and 30 s ultrasonic degassing processes. The value of 70.08 HB is obtained from ultrosonic degassing, which is equivalent to sand casting of primary Al7Si0.3Mg aluminum alloy, and the highest value of 56.4 cm for 45 s after ultrasonic degassing of fluidity was measured.

     

Evaluation of ultrasonic aluminium degassing by piezoelectric sensor

The purpose of this work was the development of a reliable technique to evaluate the intensity of acoustic cavitation during degassing of aluminium melts and to use it to select the optimum processing time for an envisaged degassing efficiency.A high sensitivity piezoelectric disk type device was used as a sensing feedback in water and liquid AlSi9Cu3 alloy. The signal acquisition and processing was carried out on a dedicated LabVIEW^® based application which allowed real-time monitoring of the piezoelectric sensor's data and ultrasonic parameters. Standard Fast Fourier Transform was applied to obtain the dominant frequencies, as well as the sub and ultra-harmonics. It was found that the amplitude of the FFT sub-harmonic (f/2) was the best indicator to evaluate the process degassing efficiency, and it could be used to select the optimal processing time, independently of other variables.The developed methodology was applied to several AlSi9Cu3 melts, and validated by measuring the final alloy densities and the volume fraction of porosities, revealing that it is an efficient, fast and cost effective technique to evaluate the degassing treatment of aluminium alloys. Experimental curves of AlSi9Cu3 alloy degassing efficiency as a function of f/2 amplitude are presented for different degassing times.